V-led는 아래에서부터 순서대로 metal substrate(p-type electrode의 역할을 함), reflector, P-GaN, MQW, N-GaN, n-electrode의 구조 순서로 쌓여있는 것을 확인할 수 있다.
기존의 LED와는 다르게 metal substrate를 지지대로 붙어 있기 때문에 p-type electrode가 n-type보다 아래쪽으로 오도록 배열시킨 특이한 구조이다. 또한 아랫부
Absorption: 외부에서 photon이 흡수되는 과정으로, semiconductor의 bandgap보다 큰 에너지를 가지는 경우에만 흡수 된다. 단 bandgap보다 너무 큰 경우는 auger electron을 생성하므로 실질적인 absorption을 일으키지 못한다.
Generation: absorption으로 electron이 excite 되면서 electron-hole pair가 생성된다
Separation: 이 두 carrier들
2. Thermal Equilibrium
Fermi level for the first time (Figure 3(c)) of the dash-dot line) is drawn.
Semiconductor conduction band and valence band of the neutral zone draw. To display the semiconductor doping level of Fermi level for the proper placement of the band (as shown in Figure 3-a in the neutral zone - energy band diagram, the same must be present.
In depletion layer
structure, we should consider non ideal effects when measure the capacitance according to applied voltage. They are 'fixed charge', 'mobile charge', and 'surface states'. When the fixed charge exists in oxide layer, it causes entire curve of graph to shift to the [Figure 12] C-V graph shift by direction of bias
side. These charges are generated by ions came in the process of deposition of oxide
4. Equipment
4.1 RCA cleaning
RCA cleaning is a series of rinsing procedure prior to experiment with Si wafer. The purpose of the RCA clean is to remove organic contaminants (such as dust particles, grease or silica gel) from the wafer surface. There are three steps to be performed. The first step is to remove organic contaminant from surface of wafer. Second step is to remove any oxide layer